Folding knife



FIG. 1 is a top, front and right side perspective view of a folding knife showing my new design;

FIG. 2 is a bottom, rear and left side perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof; and,

FIG. 9 is an enlarged view of portion 9 in FIG. 1.

The broken lines in the drawings illustrate portions of the folding knife which form no part of the claimed design. 

CLAIM The ornamental design for a folding knife, as shown and described. 